Former first lady Rosalynn Carter has been diagnosed with dementia, The Carter Center announced on Tuesday.

"She continues to live happily at home with her husband, enjoying spring in Plains and visits with loved ones," The Carter Center said in a statement.

Carter's husband, former President Jimmy Carter, has been receiving hospice care since February following years of health setbacks and, more recently, a series of hospitalizations.

The Carters are the longest-ever married presidential couple, having wed in 1946. At 98, Jimmy Carter is the oldest living former president and the longest-lived former president in U.S. history.

He and Rosalynn Carter, 95, founded The Carter Center in Georgia in 1982, shortly after Jimmy Carter lost reelection to Ronald Reagan.

In the decades since, The Carter Center has become a noted international humanitarian force, focused on public health and human rights, among other efforts. The Carters have also become well-known for their long association building houses with Habitat for Humanity.

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